An example of an organ whose regulatory function is responsive to light sensed by the eyes is the pineal gland which secretes the hormone melatonin. The hormone is released during periods of darkness while production is abruptly halted when the eyes perceive bright light. Melatonin is distributed throughout the body via blood and cerebrospinal fluid and can effect the function of organs by which it is metabolized to thereby influence sleep cycles, feeding cycles, reproduction cycles and other biological rhythms. It has therefore been suggested that phototherapy may effectively be employed to correct a melatonin imbalance which may have resulted from, for example, shift work, jet lag or life in the Polar Regions, and thereby remedy the accompanying symptoms.
Millions of North Americans feel the effects of malillumination which causes poor work conditions and can result in less energy and productiveness. Poor lighting environments can cause increased depression and even result in more severe cases called Seasonal Affective Disorder (SAD). This problem increases more and more as the winter months bring shorter and shorter days. Sunlight starvation also effects millions more in the form of a milder form called Winter Blues.
Simulated full spectrum light is color corrected light that operates in the range of 400 to 800 nanometers. This light simulates the optical brilliance of outdoor light at noontime. This light can be measured by two numbers, the Color Rendering Index (CRI) and the Kelvin Temperature or (Degrees Kelvin). The secret to true color light and optically balanced light is how close you can get to the optics of natural light. The sun at noon has a natural color temperature of 100 CRI and between 5000 and 5500 degrees Kelvin. Both CRI and Kelvin are important for the simulation sunlight.
When light is simulated that matches the optical brilliance of sunlight pupils in one's eyes become smaller. This response generates clearer vision and higher perception. The results are lower glare and eye fatigue. When Lux intensity is combined with high CRI and balanced Kelvin temperature, quality light is obtained that not only matches the optical brilliance of the sun, but reduces levels of melatonin and the stress hormone, cortisol. Full spectrum light is not blue light or daylight color. It is clear, brilliant, white light and simulates the exact color of sunlight at noon. Many people currently progress through life missing sunlight because of the enormous amounts of time that are spent indoors.